Responses in multiple myeloma should be assigned according to serum, not urine, free light chain measurements

Novel Approach to Rule-Out Unnecessary Urine Bence Jones Protein Testing: A Serum Free Light Chain Algorithm

Background/Objectives: Bence Jones proteins (BJPs) are monoclonal immunoglobulin free light chains (FLCs) that appear in the urine of patients with plasma cell disorders, including multiple myeloma (MM), Waldenström's macroglobulinemia (WM), or light chain amyloidosis (AL). Their presence can provide valuable information about disease progression and treatment efficacy. These proteins are typically detected through a 24-h urine collection, as recommended by clinical guidelines. However, this method can be inconvenient for both patients and laboratory personnel due to its time-consuming nature and the potential for collection errors. We propose an algorithm based on serum FLC (sFLC) to rule out the presence of BJPs and diminish the need for urine testing. Methods: A retrospective data analysis of 268 serum and urine samples from 44 patients with MM was performed, and cutoffs were established to predict BJP absence: total urine protein (0.115 g/L), sFLC κ/λ ratio (>0.82 λ monoclonality and <1.99 κ monoclonality), and difference of involved-uninvolved FLC (dFLC; <11.93 mg/L). A subsequent algorithm validation was performed in 716 samples from patients who underwent the same testing in routine 2023 other laboratory activity. Results: The validation of these cutoffs to rule out the presence of BJP showed that, if the protocol based on the sFLC κ/λ ratio and dFLC had been applied, 42% of the urine studies would have been avoided, achieving a sensitivity of 93.9% and a false negative rate of 6.11%. Conclusions: We propose a laboratory work protocol that would allow for the avoidance of almost half of the 24-h urine studies based on sFLC measurement, a faster and more objective alternative to urine analysis for screening out the presence of BJP, with a good sensitivity and a low false negative rate.

Daratumumab, cyclophosphamide, bortezomib, and dexamethasone for transplant-ineligible myeloma: AMaRC 03-16

ABSTRACT

In newly diagnosed transplant-ineligible patients with myeloma, daratumumab has improved outcomes when added to the standard-of-care regimens. In a randomized trial, we tested whether similar improvements would be observed when daratumumab was added to the bortezomib, cyclophosphamide, and dexamethasone (VCD) regimen. Transplant-ineligible patients with untreated myeloma were randomized to receive VCD or VCD plus daratumumab (VCDD). A total of 121 patients were randomized: 57 in the VCD arm and 64 in the VCDD arm. Baseline characteristics were balanced between the 2 arms. The median progression-free survival (PFS) was 16.8 months (95% confidence interval [CI], 15.3-21.7) and 25.8 months (95% CI, 19.9-33.5) in the VCD and VCDD arms, respectively (hazard ratio, 0.67; log-rank test P = .066). In a preplanned analysis, it was demonstrated that the daratumumab-containing arm showed a significant improvement in PFS from 18 months onward, based on estimates at fixed time points after randomization. The proportions of patients who were progression-free at the following time points were: 18 months, 48% vs 68% (P = .0002); 24 months, 36% vs 52% (P = .0001); and 30 months, 27% vs 41% (P < .0001) in the VCD and VCDD arms, respectively. The best overall response and very good partial response rate were significantly higher in the daratumumab arm compared with the VCD and VCDD arms, respectively (65% vs 86%, P = .007; and 28% vs 52%, P = .009). Seventy-two percent of the VCDD patients completed the 9 cycles of induction therapy with no grade 3 or 4 peripheral neuropathy adverse events. This study supports VCDD as an option for the initial treatment of transplant-ineligible patients with myeloma. This trial was registered at the Australian New Zealand Clinical Trials Registry (ACTRN12617000202369).

From Multiple Myeloma to Acute Myeloid Leukemia: A Case Report of a 61-year-old Woman after 8 Years of Chemotherapy and Immunotherapy

BACKGROUND

As the second most prevalent hematologic malignancy, multiple myeloma (MM) affects plasma cells and is characterized by chromosomal abnormalities, particularly involving the immunoglobulin heavy chain switch region. MM represents a biologically and clinically heterogeneous hematological malignancy that serves as a clonal evolution model, exhibiting clonal heterogeneity throughout all stages from monoclonal gammopathy undetermined significance (MGUS) and smoldering multiple myeloma (SMM) to MM. Although significant progress has been made in the treatment of MM, leading to improved patient outcomes, concerns are arising regarding disease relapse due to the presence and selection of pre-existing resistant clones or selective pressure during therapy.

CASE PRESENTATION

We present a case of multiple myeloma (MM) in a female patient, who underwent an 8-year course of treatment, including chemotherapy, immunomodulators, hematopoietic stem cell transplantation, CD38 monoclonal antibody, and chimeric antigen receptor T-cell (CAR-T), and was recently diagnosed with concurrent progressive MM and acute myeloid leukemia (AML). This patient has witnessed the evolution of MM treatment paradigms.

CONCLUSION

In this course, disease relapses occurred twice, one of which was manifested by a light chain escape (LCE). Moreover, through the course of the disease in this patient, we review the process of clonal evolution that may be relevant.

Role of serum-free light chain assay for defining response and progression in immunoglobulin secretory multiple myeloma

The International Myeloma Working Group (IMWG) guidelines recommend using electrophoresis and immunofixation to define response and progressive disease (PD) in immunoglobulin (Ig) secretory multiple myeloma (Ig-MM), whereas the role of serum-free light chain (sFLC) is controversial. We retrospectively analyzed the value of adding sFLC assays in the definition of response and PD according to IMWG criteria in 339 Ig-MM patients treated with a first-line novel agent-based therapy (median follow-up 54 months). sFLC PD was defined according to conventional criteria plus increased sFLC levels, or sFLC escape (sFLCe); progression/sFLCe-free survival (ePFS) was the time from the start of treatment to the date of first PD or sFLCe, or death; overall survival after PD/sFLCe (OS after Pe) was the time from first PD or sFLCe to the date of death. 148 (44%) patients achieved a complete response and 198 (60%) a normal sFLC ratio (sFLCR). sFLCR normalization was an independent prognostic factor for extended PFS (HR = 0.46, p = 0.001) and OS (HR = 0.47, p = 0.006) by multivariable analysis. 175 (52%) patients experienced PD according to the IMWG criteria, whereas 180 (53%) experienced PD or sFLCe. Overall, a sFLCe was observed in 31 (9%) patients. Median PFS and ePFS were both equal to 36 (95% CI = 32-42, and 32-40, respectively) months. sFLC PD adversely affected the OS after Pe compared to PD with increasing monoclonal Ig only (HR = 0.52, p = 0.012). Our results support the inclusion of the sFLC assay for defining response and PD in Ig-MM.

Can urine studies be replaced by serum free light chains measurements to assign responses in multiple myeloma patients?

Serum and urine protein electrophoresis and immunofixation are the preferred techniques for monitoring monoclonal proteins and evaluating treatment response in multiple myeloma (MM) patients with measurable disease. However, urine studies are subjected to limitations that may lead to inaccuracies or prevent guidelines compliance. We retrospectively studied if the substitution of urine studies by measuring serum free light chains (sFLCs) results in a comparable disease monitoring, both in intact immunoglobulin (II) and light chain (LC) MM patients. In our cohort, equal or higher percentages of disease were identified by sFLCs at baseline and maximum response as compared to urine studies. Achieving very good partial response or better (≥VGPR) according to the response criteria proposed by the French group (evaluating sFLCs instead of urine) and the IMWG response criteria were associated to a 62% and 63% reduced risk of progression, respectively. A similar prognostic value for reaching ≥VGPR was also observed among LCMM patients when the French group and the IMWG response criteria were applied. Overall, these results support the replacement of urine studies by the sFLCs assay in IIMM. In LCMM, sFLCs could be used for monitoring and urine studies could be performed only to confirm complete remissions and progressions.

Phase 2 studies of lenalidomide, subcutaneous bortezomib, and dexamethasone as induction therapy in patients with newly diagnosed multiple myeloma

There are limited prospective data on lenalidomide, subcutaneous bortezomib, and dexamethasone (RsqVd) in transplant-eligible/transplant-ineligible patients with newly diagnosed multiple myeloma. Reliable biomarkers for efficacy and toxicity are required to better tailor therapy. Two parallel studies were conducted by Cancer Trials Ireland (CTI; NCT02219178) and the Dana-Farber Cancer Institute (DFCI; NCT02441686). Patients received four 21-day cycles of RsqVd and could then receive either another 4 cycles of RsqVd or undergo autologous stem cell transplant. Postinduction/posttransplant, patients received lenalidomide maintenance, with bortezomib included for high-risk patients. The primary endpoint was overall response rate (ORR) after 4 cycles of RsqVd. Eighty-eight patients were enrolled and 84 treated across the two studies; median age was 64.7 (CTI study) and 60.0 years (DFCI study), and 59% and 57% had stage II-III disease. Pooled ORR after 4 cycles in evaluable patients was 93.5%, including 48.1% complete or very good partial responses (CTI study: 91.9%, 59.5%; DFCI study: 95.0%, 37.5%), and in the all-treated population was 85.7% (44.0%). Patients received a median of 4 (CTI study) and 8 (DFCI study) RsqVd cycles; 60% and 31% of patients (CTI study) and 33% and 51% of patients (DFCI study) underwent transplant or received further RsqVd induction, respectively. The most common toxicity was peripheral neuropathy (pooled: 68%, 7% grade 3-4; CTI study: 57%, 7%; DFCI study: 79%, 7%). Proteomics analyses indicated elevated kallikrein-6 in good versus poor responders, decreased midkine in good responders, and elevated macrophage inflammatory protein 1-alpha in patients who stopped treatment from neurotoxicity, suggesting predictive biomarkers warranting further investigation.

To skim or splice? Comparing the quantification of M-proteins using two peak-integration protocols across multiple electrophoresis platforms

OBJECTIVES

M-protein quantification by peak integration in serum protein electrophoresis (SPE) plays a central role in diagnosing, prognosing and monitoring monoclonal gammopathies. The conventional perpendicular drop (PD) integration approach integrates M-spikes from the baseline, which performs acceptably when the M-protein concentration is relatively high compared to the amount of background proteins present. The alternative peak-integration protocol by tangential skim (TS), however, allows for more accurate M-protein estimations by excluding background proteins. Despite some guideline recommendations, TS has been poorly adopted, making an understanding of the differences between the two protocols and their potential impacts paramount when considering a change from PD to TS.

DESIGN & METHODS

We conducted retrospective investigations of the differences in M-protein quantification over large concentration ranges between PD and TS on 3 of the most popular electrophoresis platforms.

RESULTS

Compared to PD, TS gave consistently lower results; the differences between the two methods increased tremendously and became more sporadic as M-protein concentrations dropped below 15 g/L in all 3 platforms. At < 15 g/L, the average % difference ranged from -81 % to -95 %, while above 15 g/L, the average % difference was only -13 to -31 %. Medical decision point analyses using linear regression predicted statistically significant and platform-dependent differences, which could impact clinical interpretation.

CONCLUSIONS

Careful consideration of the magnitude of concentration changes and the potential impacts on patient classification and management should be made when switching to TS for M-protein quantification.

Prognostic Impact of Serum Free Light Chain Ratio Normalization in Patients with Multiple Myeloma Treated within the GMMG-MM5 Trial

Simple Summary

For multiple myeloma (MM) patients with measurable disease, there is no recommendation to monitor serum free light chains during therapy. However, this could provide important information in terms of prognosis. We investigated the prognostic impact of serum free light chain ratio (FLCr) normalization in 590 patients with secretory MM during first-line treatment within the German-Speaking Myeloma Multicenter Group MM5 trial. We are able to show that there is an increasing percentage of patients who achieve FLCr normalization during therapy. Importantly, we demonstrate that FLCr normalization at any time before the start of maintenance is significantly associated with prolonged progression-free and overall survival in multivariable time-dependent Cox regression analyses. This suggests that FLCr normalization during therapy is an important and simple way to assess prognostic factor in MM and supports the serial measurement of serum free light chains during therapy, even in patients with secretory MM.

Abstract

We investigated the prognostic impact of time-dependent serum free light chain ratio (FLCr) normalization in 590 patients with secretory multiple myeloma (MM) during first-line treatment within the German-Speaking Myeloma Multicenter Group MM5 trial. Serum free light chains (sFLC) were assessed by the Freelite test at baseline, after induction, mobilization, autologous blood stem cell transplantation, consolidation and every three months during maintenance or follow up within two years after the start of maintenance. The proportion of patients with a normal or normalized FLCr increased from 3.6% at baseline to 23.2% after induction and 64.7% after consolidation. The achievement of FLCr normalization at any one time before the start of maintenance was associated with significantly prolonged progression-free survival (PFS) (p < 0.01, hazard ratio (HR) = 0.61, 95% confidence interval (95% CI) = 0.47–0.79) and overall survival (OS) (p = 0.02, HR = 0.67, 95% CI = 0.48–0.93) in multivariable time-dependent Cox regression analyses. Furthermore, reaching immune reconstitution, defined as the normalization of uninvolved immunoglobulins, before maintenance was associated with superior PFS (p = 0.04, HR = 0.77, 95% CI = 0.60–0.99) and OS (p = 0.01, HR = 0.59, 95% CI = 0.41–0.86). We conclude that FLCr normalization during therapy is an important favorable prognostic factor in MM. Therefore, we recommend serial measurements of sFLC during therapy until achieving FLCr normalization, even in patients with secretory MM.

Prediction of Early Treatment Response in Multiple Myeloma Using MY-RADS Total Burden Score, ADC, and Fat Fraction From Whole-Body MRI: Impact of Anemia on Predictive Performance

Background: The recently released Myeloma Response Assessment and Diagnosis System (MY-RADS) for multiple myeloma (MM) evaluation by whole-body MRI (WB-MRI) describes the total burden score. However, assessment is confounded by red bone marrow hyperplasia in anemia. Objective: To assess utility of the MY-RADS total burden score, ADC, and fat fraction (FF) from WB-MRI in predicting early treatment response in patients with newly diagnosed MM and to compare these measures' utility between patients with and without anemia. Methods: This retrospective study included 56 patients (mean age 57.4±9.6 years; 40 men, 16 women) with newly diagnosed MM who underwent baseline WB-MRI including DWI and mDixon sequences. Two radiologists recorded total burden score using MY-RADS and measured ADC and FF of diffuse and focal disease sites. Mean values across sites were derived. Interobserver agreement was evaluated; readers' mean assessments were used for further analyses. Presence of deep response after four cycles of induction chemotherapy was recorded. Patients were classified as anemic if having hemoglobin less than 100 g/L. Utility of WB-MRI parameters in predicting deep response was assessed. Results: A total of 24/56 patients showed deep response; a total of 25/56 patients had anemia. Interobserver agreement, expressed using intraclass correlation coefficients, ranged from 0.95 to 0.99. Among patients without anemia, those with deep response compared with those without deep response exhibited lower total burden score (9.0 vs 18.0), lower ADC (0.79x10-3mm²/s vs 1.08x10-3mm²/s), and higher FF (0.21 vs 0.10) (all p<.001). The combination of these three parameters (optimal cutoffs: <15 for total burden score, <0.84×10-3mm²/s for ADC, >0.16 for FF) achieved sensitivity of 93.8%, specificity of 93.3%, and accuracy of 93.5% for predicting deep response. In patients with anemia, none of the three parameters were significantly different between those with and without deep response (all p>.05), and the combination of parameters achieved sensitivity of 56.3%, specificity of 100.0%, and accuracy of 72.0%. Conclusion: Low total burden score, low ADC, and high FF from WB-MRI may predict deep response in MM, though only among those patients without anemia. Clinical Impact: WB-MRI findings may help guide determination of prognosis and initial treatment selection in MM.

Historical perspectives in clinical pathology: Bence Jones protein-early urine chemistry and the impact on modern day diagnostics

This is the third in the series of historical articles dealing with developments in clinical pathology. Bence Jones proteins are immunoglobulin light chains found in excessive quantities in urine in multiple myeloma and are believed to be one of the first tumour markers ever discovered . Dr Henry Bence Jones is credited with the discovery of this protein in 1847 that bears his name and he can also be regarded as the first chemical pathologist/clinical chemist. Since then, numerous advances and refinements have been made in the measurement and detection of urine light chain proteins which have resulted in the current sensitive serum free light chain assays used today.

Serum free light chains and multiple myeloma: Is it time to extend their application?

In nonsecretory, oligo-secretory, and light chain multiple myeloma patients, serial sFLC evaluation could precede biochemical and clinical disease progression, even in extramedullary relapse, thus initiating early treatment with novel anti-MM agents.

Comparison of MALDI-TOF mass spectrometry analysis of peripheral blood and bone marrow-based flow cytometry for tracking measurable residual disease in patients with multiple myeloma

Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) may soon replace routine electrophoretic methods for monitoring monoclonal proteins in patients with multiple myeloma. To further evaluate the clinical utility of this assay, we compared the performance of MALDI-TOF-MS head-to-head with an established bone marrow-based measurable residual disease assay by flow cytometry (Flow-BM-MRD), using Memorial Sloan Kettering Cancer Center's 10-color, single-tube method. Our results suggest that MALDI-TOF-MS adds value to bone marrow-based MRD testing and may be most useful for early detection of relapse in peripheral blood compared to current electrophoretic methods.

Early monoclonal protein decline pattern is an independent prognostic factor in patients with multiple myeloma

Patients always have different responses to the same treatment due to the heterogeneity of multiple myeloma (MM). However, the relationship between monoclonal protein (M-protein) reduction rates during treatment and survival prognosis in MM patients remains controversial. We retrospectively analyzed 198 newly diagnosed MM patients who received regular bortezomib-based chemotherapy for at least 2 cycles and subsequent autologous stem cell transplantation (ASCT) plus continuous maintenance. The relationship between the early M-protein reduction rates and survival prognosis was evaluated. This study is the first to divide patients into three patterns, namely, A, B, and C, according to the M-protein reduction rate during the first two therapy cycles. The results showed that pattern B patients with progressive reduction in M-protein had better progression-free survival (PFS) and overall survival (OS) than did pattern A or C patients with precipitating or slow M-protein reduction (75.33 ± 18.81 versus 41.23 ± 9.13 or 26.60 ± 6.67 months; P < 0.001; 117.33 ± 18.44 versus 71.00 ± 10.06 or 39.73 ± 24.10 months; P = 0.003, respectively). In addition, biological analysis showed that pattern A + C patients had higher international staging system (ISS) stage III proportions (P = 0.008) and lactate dehydrogenase (LDH) elevations (P = 0.044) than pattern B patients. Furthermore, pattern A + C was a significant independent adverse parameter for PFS and OS (HR = 2.62, P = 0.001; HR = 2.15, P = 0.022, respectively). Thus, our results demonstrate that pattern A + C indicates an inferior survival prognosis in MM.

Role of urine immunofixation in the complete response assessment of MM patients other than light-chain-only disease

Response criteria for multiple myeloma (MM) require monoclonal protein (M-protein)–negative status on both serum immunofixation electrophoresis (sIFE) and urine (uIFE) immunofixation electrophoresis for classification of complete response (CR). However, uIFE is not always performed for sIFE-negative patients. We analyzed M-protein evaluations from 384 MM patients (excluding those with light-chain-only disease) treated in the GEM2012MENOS65 (NCT01916252) trial to determine the uIFE-positive rate in patients who became sIFE-negative posttreatment and evaluate rates of minimal residual disease (MRD)–negative status and progression-free survival (PFS) among patients achieving CR, CR but without uIFE available (uncertain CR; uCR), or very good partial response (VGPR). Among 107 patients with M-protein exclusively in serum at diagnosis who became sIFE-negative posttreatment and who had uIFE available, the uIFE-positive rate was 0%. Among 161 patients with M-protein in both serum and urine at diagnosis who became sIFE-negative posttreatment, 3 (1.8%) were uIFE positive. Among patients achieving CR vs uCR, there were no significant differences in postconsolidation MRD-negative (&lt;10−6; 76% vs 75%; P = .9) and 2-year PFS (85% vs 88%; P = .4) rates; rates were significantly lower among patients achieving VGPR. Our results suggest that uIFE is not necessary for defining CR in MM patients other than those with light-chain-only disease.